It is known to place heating, ventilation and air conditioning (HVAC) systems in the roof of a vehicle, such as a tractor. Such a roof-mounted HVAC system for a tractor is shown in U.S. patent application Ser. No. 11/518,050 filed 8 Sep. 2006 and assigned to the assignee of this application. Such an HVAC system will include an evaporator which condenses water as a byproduct of cooling the air moving through it. Most HVAC units have a drain pan under the evaporator, to collect this water, which is connected to a hose to port it out of the vehicle.
With such a roof mounted HVAC system condensed water from the evaporator sometimes can leak out of its containment area to soak the headliner and drip on the operator's head. Also, with hot coolant overhead there needs to be an efficient way to drain it in the event of a heater coil failure. Upon failure, a heater coil may send several gallons per minute of hot coolant into the roof over the operators head. Most drain systems cannot handle such a failure.
When a vehicle runs for a long time on a steep slope it may lose containment of the water, or if the drain lines do not carry the water away, the water can collect until the attitude of the vehicle changes. This is a very common problem when working on steep slopes and gravity prevents the drain lines from draining the water away. Under these circumstances, the water can collect until the attitude of the vehicle changes, causing spillage.
A drain line can also become plugged by mud, insects, and debris.
There is a need for a drainage system to solve such problems, and to help assure that all condensation is routed to proper drains, despite the vehicle tilting, rolling or bouncing over rough terrain.